Skin cancer is one of the most common cancers in the United States, and it is also one of the most preventable. Preventive behaviors include reducing peak sun exposure, wearing sunscreen, seeking shade, wearing protective clothing, and avoiding sunburn. Few skin cancer prevention programs in outdoor settings have been evaluated in controlled trials, and even fewer have been studied when widely disseminated. Of special importance, most skin cancer intervention trials rely largely on self-reported behavior change as an endpoint. The Pool Cool Diffusion Trial (CA 92505; 2003-2007) is evaluating the effects of two strategies for diffusion of the Pool Cool skin cancer prevention program -- in aquatics settings -- on: program implementation, maintenance, and sustainability; organizational and environmental supports for sun protection; and sun protection habits and sunburns among children. The main health behavior and environmental endpoints are based on survey self-reports from participants, with limited corroboration of findings from observations. With the advent of new photobiology methods, it is now possible to compare self-reports with more objective assessments including observations. The aims of the proposed supplement are to: test the validity of self-report measures of ultraviolet radiation (UVR) exposure and sun protection by completing objective biological measures on a sample of study participants, and comparing those reports with self-report survey data. Specifically, we propose to study 480 individuals, 160 each in three categories: lifeguards, parents, and their children aged 5 to 10 years. For each participant we will systematically collect survey and diary measures, and compare them with objective measures of UVR exposure (polysulphone dosimeters), and of sun protection (observation and sunscreen swabbing). These data will enable us to estimate the associations, and if applicable, the magnitude and direction of systematic error in self-report of UVR exposure and sun protection, among various sub-groups of study participants. In addition, we can conduct fine-grained analyses of parent-child associations in behaviors and in accuracy of self-reports. This supplementary research will apply state-of-the-science multidisciplinary measurement techniques to a major public health problem, thus advancing the science of health behavior measurement and elucidating the findings from this major diffusion study. It also provides a novel model for improving health behavior change research. [unreadable] [unreadable]